Optical coherence tomography (OCT) is a rapidly advancing imaging modality with broad applications in biomedical and industrial imaging. Originally reduced to practice at MIT in the early 1990's, the first generation of OCT achieved clinical success as a diagnostic tool for retinal pathologies. This first generation technology relied on a moving reference mirror in a fiber-interferometric geometry. The interferometer output a signal whose strength squared was in direct proportion to backscattered power of light from within the subject under test, specifically at the depth where the path length into the sample matched the path length to the movable reference mirror. This technique is known as a time-domain technique, and advantages in simplicity of architecture and signal interpretation are overcome by a low signal-to-noise ratio and slow imaging speed.
More recently, a new class of OCT imaging technology has emerged that may address some of the disadvantages of the time-domain approach. Fourier domain OCT relies on acquiring a frequency-domain signature and polling the depth of the sample in one pass. This parallel acquisition of the depth-dependent backscattered light leads to from about 15 to about 20 dB increase in the signal to noise ratio (SNR), and this advantage in SNR may readily be turned to faster imaging, higher quality images, or both. Commercial systems that deploy Fourier domain technology have recently reached the market and are aiming at replacing first generation systems with systems that acquire images up to 50 times faster.
While this speed increase on its own is valuable to the user, the Fourier domain approach offers both additional advantages and additional complexity that offer associated benefits and risks. Generating an image in the Fourier domain approach requires Fourier-transformation of frequency domain (wavelength or wavenumber) data. Opportunities for optimizing Fourier domain OCT imaging systems lie in real-time signal processing, image optimization, and management and utilization of the high data-content images.